1. Filed of the Invention
The present invention relates to a method for producing an optically active chrysanthemic acid (cyclopropanecarboxylic acid) derivative.
2. Description of the Related Art
Optically active cyclopropanecarboxylic acid derivatives are important intermediates for drugs and pesticides. For example, (+)-2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylic acid known as chrysanthemum mono-carboxylic acid constitutes an acid component of synthetic pyrethroid insecticide.
The insecticidal activity of a trans-pyrethroid ester is usually higher than that of a cis-isomer. Particularly, pyrethroid esters of (+)-trans-chrysanthemum mono-carboxylic acid(hereinafter referred to as "chrysanthemic acid") or chrysanthemic acid enriched with the (+)-trans-chrysanthemic acid have exhibited excellent insecticidal activity. Accordingly, an industrially advantageous method to produce (+)-trans-chrysanthemic acid or chrysanthemic acid enriched with the (+)-trans-chrysanthemic acid has been desired.
As a method of producing an optically active chrysanthemic acid derivative by using a synthetic technique, there has been known a method of reacting a (.+-.)-trans-chrysanthemum mono-carboxylic acid or trans rich (.+-.)-chrysanthemum mono-carboxylic acid with an optical resolution agent, which are an optically active amine, to obtain an optically active chrysanthemic acid (JP46-20382B/1971, JP54-37130B/1979, JP49-109344A/1974 and JP51-23497B/1976). However, these optical resolution methods were not always satisfactory, because of low yield of the desired optically active chrysanthemic acid.
Therefore, the present inventors have intensively studied. As a result, they have found that, when chrysanthemic acid optically enriched with one isomer, e.g. (+)-trans-chrysanthemic acid can be purified by crystallization using an optical active amine in the production of an optically active chrysanthemic acid, whereby (+)-trans-chrysanthemic acid having excellent optical purity can be obtained with surprisingly good efficiency compared with the case of using racemic chrysanthemic acid, and trans isomer ratio of the chrysanthemic acid can also be improved efficiently when trans isomer having not less than 50% trans-isomer ratio are applied.